Drying apparatus, printing system and drying method that inject hot wind from nozzles to surface of recording medium

Abstract

In the air-blow dryers 7a, 7b, the back surface M2 of the printing medium M is supported by the rollers 74 while the hot wind is injected from the nozzles 76u to the front surface M1 of the printing medium M. By extending the printing medium M along the rollers 74, the evaporation of the moisture can be promoted by the hot wind while the formation of creases of the printing medium M is suppressed against the influence of the temperature distribution caused by the latent heat of the moisture on the printing medium M. After a certain amount of the moisture is evaporated, the temperature of the printing medium M becomes relatively uniform. In the air-blow dryers 7c, 7d, the printing medium M is dried by injecting the hot wind to the printing medium M from the nozzles 76l and 76u from both sides.

What is claimed is: 
     
       1. A drying apparatus, comprising:
 a conveyor which conveys a printing medium having a recording surface and a non-recording surface opposite to the recording surface, an aqueous ink adhering to the recording surface; 
 a preceding-stage dryer which dries the printing medium being conveyed by the conveyor; 
 a next-stage dryer which dries the printing medium being conveyed by the conveyor on a side downstream of the preceding-stage dryer in a moving direction of the printing medium conveyed by the conveyor; and 
 a housing accommodating the conveyor, the preceding-state dryer, and the next-stage dryer, 
 wherein: 
 the preceding-stage dryer includes a plurality of first nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on a recording surface side of the printing medium and a plurality of rotary bodies arrayed in the moving direction of the printing medium conveyed by the conveyor on a non-recording surface side of the printing medium, 
 the first nozzles inject a hot wind of 60° C. or higher to the recording surface, 
 the rotary bodies have peripheral surfaces configured to contact the non-recording surface of the printing medium and rotate, following the printing medium, 
 the next-stage dryer includes a plurality of second nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on the recording surface side of the printing medium and a plurality of third nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on the non-recording surface side of the printing medium, 
 the second nozzles inject the hot wind to the recording surface, 
 the third nozzles inject the hot wind to the non-recording surface, and 
 the housing further accommodates an exhaust unit that exhausts air in the housing to outside of the housing. 
 
     
     
       2. The drying apparatus according to  claim 1 , wherein the first nozzles and the rotary bodies are arranged in a staggered manner in the moving direction of the printing medium conveyed by the conveyor in the preceding-stage dryer. 
     
     
       3. The drying apparatus according to  claim 1 , wherein the second nozzles and the third nozzles are arranged in a staggered manner in the moving direction of the printing medium conveyed by the conveyor in the next-stage dryer. 
     
     
       4. The drying apparatus according to  claim 1 , wherein:
 the preceding-stage dryer includes a fourth nozzle arranged upstream of the most upstream rotary body, out of the plurality of rotary bodies, in the moving direction of the printing medium conveyed by the conveyor on the non-recording surface side of the printing medium, and 
 the fourth nozzle injects the hot wind to the non-recording surface. 
 
     
     
       5. The drying apparatus according to  claim 1 , wherein there is a clearance between the first nozzles and the peripheral surfaces of the rotary bodies when viewed from the moving direction of the printing medium conveyed by the conveyor in the preceding-stage dryer, and the printing medium is supported with the recording surface separated from the first nozzles and the non-recording surface held in contact with the rotary bodies if the injection of the hot wind from the first nozzles is stopped. 
     
     
       6. The drying apparatus according to  claim 1 , wherein the next-stage dryer is arranged below the preceding-stage dryer in a vertical direction. 
     
     
       7. The drying apparatus according to  claim 6 , wherein:
 a moving direction of the printing medium conveyed by the conveyor in the preceding-stage dryer and a moving direction of the printing medium conveyed by the conveyor in the next-stage dryer are opposite, and 
 the conveyor includes a preceding-stage inverter which bends the printing medium conveyed from the preceding-stage dryer downward and further bends the printing medium toward the next-stage dryer. 
 
     
     
       8. The drying apparatus according to  claim 7 , wherein:
 the conveyor conveys the printing medium in the preceding-stage dryer with the recording surface facing up and the non-recording surface facing down and conveys the printing medium in the next-stage dryer with the recording surface facing down and the non-recording surface facing up, 
 the first nozzles are arranged above the printing medium conveyed by the conveyor, 
 the rotary bodies are arranged below the printing medium conveyed by the conveyor, 
 the second nozzles are arranged below the printing medium conveyed by the conveyor, and 
 the third nozzles are arranged above the printing medium conveyed by the conveyor. 
 
     
     
       9. The drying apparatus according to  claim 7 , further comprising a succeeding-stage dryer which dries the printing medium by injecting a gas toward the recording surface of the printing medium being conveyed by the conveyor on a side downstream of the next-stage dryer in the moving direction of the printing medium conveyed by the conveyor, wherein:
 the succeeding-stage dryer is arranged below the next-stage dryer in a vertical direction, 
 the succeeding-stage dryer includes a plurality of fifth nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on the recording surface side of the printing medium and a plurality of sixth nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on the non-recording surface side of the printing medium, 
 the fifth nozzles inject the hot wind to the recording surface, and 
 the sixth nozzles inject the hot wind to the non-recording surface. 
 
     
     
       10. The drying apparatus according to  claim 9 , wherein:
 a moving direction of the printing medium conveyed by the conveyor in the next-stage dryer and a moving direction of the printing medium conveyed by the conveyor in the succeeding-stage dryer are opposite, and 
 the conveyor includes a next-stage inverter which bends the printing medium conveyed from the next-stage dryer downward and further bends the printing medium toward the succeeding-stage dryer. 
 
     
     
       11. The drying apparatus according to  claim 1 , wherein the preceding-stage dryer and the next-stage dryer are arrayed in a horizontal direction. 
     
     
       12. The drying apparatus according to  claim 1 , further comprising a heating unit to heat the rotary bodies. 
     
     
       13. A printing system, comprising:
 a printing apparatus which adheres an aqueous ink to a recording surface of a printing medium having the recording surface and a non-recording surface opposite to the recording surface; and 
 the drying apparatus according to  claim 1 , 
 the printing medium having the aqueous ink adhered thereto by the printing apparatus being dried by the drying apparatus. 
 
     
     
       14. The printing system according to  claim 13 , further comprising a coating apparatus which applies a primer to the recording surface of the printing medium, wherein:
 the printing apparatus adheres the aqueous ink to the recording surface having the primer applied thereto by the coating apparatus. 
 
     
     
       15. A drying method, comprising:
 a conveying step of conveying a printing medium having a recording surface to which an aqueous ink adhered and a non-recording surface opposite to the recording surface by a conveyor; 
 a preceding-stage drying step of drying the printing medium being conveyed by the conveyor by a preceding-stage dryer; 
 a next-stage drying step of drying the printing medium being conveyed by the conveyor by a next-stage dryer on a side downstream of the preceding-stage dryer in a moving direction of the printing medium conveyed by the conveyor; and 
 an exhausting step of exhausting air in a housing, by an exhaust unit, to outside of the housing, the housing accommodating the conveyor, the preceding-state dryer, the next-stage dryer, and the exhaust unit, 
 wherein: 
 the preceding-stage dryer includes a plurality of first nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on a recording surface side of the printing medium and a plurality of rotary bodies arrayed in the moving direction of the printing medium conveyed by the conveyor on a non-recording surface side of the printing medium, 
 the first nozzles inject a hot wind of 60° C. or higher to the recording surface, 
 the rotary bodies have peripheral surfaces configured to contact the non-recording surface of the printing medium and rotate, following the printing medium, 
 the next-stage dryer includes a plurality of second nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on the recording surface side of the printing medium and a plurality of third nozzles arrayed in the moving direction of the printing medium conveyed by the conveyor on the non-recording surface side of the printing medium, 
 the second nozzles inject the hot wind to the recording surface, and 
 the third nozzles inject the hot wind to the non-recording surface.